Brain stem auditory evoked response (BAER), visual evoked response (VER) and nerve conduction velocities (NCV) were studied in 18 insulin-dependent diabetic children between the ages of 3.5 and 16 years (mean 9.0 +/- 3.2 years). The results were compared with those of age-matched controls. The VER latencies of the diabetic children in the right eye and left eye were significantly prolonged when compared with the control group. NCV of n. peroneus and the latency of sensorial n. medianus were significantly impaired when compared with the control group. Although the latencies of waves III, IV and V of the right ear and the interpeak latencies of I-III, I-V, III-V of both ears were prolonged, the comparison with the control group was not significant. The beta 2 microglobulin levels of the diabetic patients were significantly higher than those of the control group. There was a positive correlation between the beta 2 microglobulin and the BAER interpeak latencies of wave III-V in both ears (r: 0.51 p < 0.01). There was also a positive correlation between NCVs of n. peroneus and n. medianus (motor and sensorial) with beta 2 microglobulin (r: 0.52 p < 0.01) and between VER latencies (r: 0.52 p < 0.01) of both eyes separately. In our study the prolonged latencies of VER and BAER were detected in the absence of clinical abnormalities in visual and hearing systems.(ABSTRACT TRUNCATED AT 250 WORDS)