The clinical, electrophysiological, pathological and genetic findings are described in the first Spanish family diagnosed with hereditary motor and sensory neuropathy type Lom (HMSNL) initially identified by Kalaydjeva et al. in 1996. The three affected patients belong to a non-consanguineous family with Gypsy background that were followed up over 10 years. Serial clinical and neurophysiological examinations and genetic analysis were undertaken in every patient. Sural nerve biopsy was performed in the oldest patient. The clinical features are similar to those previously described in HMSNL and all of them showed abnormal brain auditory evoked potentials. The oldest brother developed sensorineural deafness at the age of 20. Conduction velocities were unobtainable in all patients and nerves tested except for the median nerve in the youngest child in whom conduction was severely slowed. Neuropathological examination revealed a severely depleted nerve with very few surviving myelinated fibers which possessed thin myelin sheaths. Schwann cell processes were arranged in circular configurations without typical onion bulb configuration. Genetic analysis showed that the maternal chromosome inherited by all three affected siblings displayed a very unusual haplotype. Our patients show the characteristic clinical, electrophysiological and pathological findings described in HMSNL and represent the first reported Spanish family affected from the disease. The genetic findings in this family have contributed to refine the HMSNL critical linkage region.