It has an area of 2,751 sq. km., with a population of 224,969 inhabitants, of whom 224,398 are Catholics, distributed in 217 parishes, served by 215 diocesan priests and 9 regular clergy, one seminary, 2 male and 7 female religious communities (1949).
The earliest notice relating to this diocese is found in the Council of Lugo (569). Three years later, the bishop of L., Sardinario, attended the Second Council of Braga, perhaps as the first bishop of the diocese. Filipe, who took part in the Third Council of Toledo (589), was probably his successor. The diocese of L., which had been suffragan to Braga, passed under the jurisdiction of Mérida around 653. Fioncio, present at the Fifteenth Council of Toledo (688) and also at the Seventeenth (693), seems to have been the last prelate of Lamego before the Arab invasion. From this period, the names of various bishops are recorded who appear to have been only titular bishops, since residence was not possible. After the reconquest of the city by Fernando the Great between 1057 and 1064, efforts were made to renew the Christian faith. Sancho of Castile, son of Fernando, restored the see and placed at its head Bishop Pedro. However, given the precarious economic situation of the region, Pope Paschal II, with the bull *Apostolicae Sedis* of 23 March 1102, entrusted its care to the bishop of Coimbra, which gave rise to no small disputes. Hugo, bishop of Porto, went to Rome and obtained for himself the administration of the see of Lamego. The bishop of Coimbra protested against this decision. Pope Paschal II, having heard the opinions of the bishops of Toledo, Braga, Tuy, and Salamanca, then entrusted the care of the diocese once more to the bishop of Coimbra, a disposition confirmed by Pope Honorius II on 11 February 1126. At this time the diocese of Lamego was made suffragan to Compostela, to which Calixtus II had transferred the metropolitan rights of Mérida. This fact was the cause of conflicts between the archbishop of Compostela and that of Braga. Innocent III put an end to the conflicts between the two archbishops in their presence, placing the dioceses of Lamego and Guarda under the jurisdiction of the archbishop of Compostela. Pope Pius XI, with the apostolic constitution *Praedecessorum nostrorum* (AAS, 14 [1922], pp. 369–72), assigned Lamego to the ecclesiastical province of Braga.
Among its bishops is counted Tomás de Almeida, who was bishop of Porto and then the first patriarch of Lisbon.