The objective was to test the applicability of the new classification for paediatric human immonodeficiency virus infection. The person-time of each state, transition probabilities and survival (+/- standard errors) at 5 years, and median sojourn-time were calculated on 39 perinatally infected children followed up from the first month of life for a median of 64.5 (1.2-120.1) months. The person-times of the N2, N3, B1, C1, and C2 states were low. The transition probabilities and sojourn-times were similar for A (48.1 +/- 10.8%; 63.5 months), B (50.5 +/- 15.5%; 44.9 months) and C (74.6 +/- 15.1%; 43.1 months) clinical categories, which differed (p < 0.025) from the N category (87.9 +/- 5.5%; 12.05 months). The survival probabilities after 5 years of entering the A, B and C categories were 84.8 +/- 10.7%, 60.5 +/- 19.8% and 14.8 +/- 13.5%, respectively (p < 0.001). Immunological category 3 had lower transition probabilities and longer sojourn-times (58.8 +/- 16.6%; 53.3 months) than categories 1 (71.3 +/- 8.1%; 33.2 months) and 2 (75.6 +/- 10.5%; 19.8 months) (p < 0.01). The transition probabilities to C3 for states N3, A3 or B3 were 52.5 +/- 13.5%. In conclusion, the classification fits the clinical history better than the immunological history.