The Longitudinal ALS Cohort is a clinical dataset collected at the University of Padua (UNIPD) on patients with amyotrophic lateral sclerosis (ALS) and related motor neuron diseases who are followed over time in the Veneto region of Italy. The cohort brings together detailed information from routine clinical care to characterise disease onset, progression and outcomes in a real-world setting. The underlying dataset includes person-level variables grouped into several domains: demographic and administrative information; diagnostic history (including ALS subtype, dates of symptom onset, diagnosis, tracheostomy and death); family and oncological history; potential environmental and lifestyle risk factors (for example smoking, occupational exposures and trauma); neurophysiological investigations (EMG, motor evoked potentials); brain and spinal MRI and, where available, PET findings; laboratory measurements and blood gas analyses; respiratory function tests and spirometry; detailed neurological examination; medications and other interventions (including gastrostomy); and longitudinal ALS Functional Rating Scale (ALSFRS-R) scores. Clinical information is complemented, for a subset of patients, by genetic testing results and linked variant data. This Zenodo record does not expose the individual-level dataset itself. Instead, it provides documentation to support FAIR description and internal reuse within the HEREDITARY Horizon Europe project, including a structured data dictionary and a data access policy. Please refer to the dataset policy text to gain access to the sensitive data.