The results of a survey of lungworm infections in goats in the Middle Atlas and Rabat areas in Morocco during 1990-1992 are reported. Five species were recorded: Dictyocaulus filaria, Protostrongylus rufescens, Cystocaulus ocreatus, Muellerius capillaris and Neostrongylus linearis. The parasitological profile of protostrongylid species was represented by Muellerius (69-78%), Protostrongylus (16-25%) and Cystocaulus (5-6%) in the Rabat and Middle Atlas areas. Neostrongylus was virtually non-existent (under 1%) in both regions. Multigeneric infection involving several species of lungworms reached 54% in Rabat and 88% in Middle Atlas. Dictyocaulus infection of goats does not appear to be a serious problem. Infection rates of 40% and 50%, and average worm burdens of three and five worms per kid and adult goat were recorded in autumn in the Rabat area. A similar pattern was noted in Middle Atlas. In contrast, the incidence of small lungworm infections in goats is widespread at levels likely to be of economic significance. The level of infection was considerably higher than the Dictyocaulus infection and the infection rate was virtually 100% in both age groups in the two areas. The overall worm burdens averaged 77.03 +/- 22.6 parasites per adult goat and 44.16 +/- 16.3 per kid in the Rabat area, whereas the corresponding figures in Middle Atlas were 51.48 +/- 16.65 and 34.06 +/- 2.69 worms. The periods of high risk of infection by small lungworms were autumn, early winter and late spring-early summer. However, the heaviest infection by adult worms and the highest larval excretion were observed in late autumn and winter when molluscs were heavily infected. The periparturient period seemed to exert a positive influence on protostrongylid larval production. The output of first stage larvae (L1) of lungworms was significantly higher in goats than in sheep. Thus, goats may play a greater role in pasture contamination. The epidemiological factors influencing the seasonal fluctuations of lungworms are discussed and a timetable of recommended treatments is suggested.