The role of mother-child relationship and pain variables in inducing depression in mothers suffering from Rheumatoid Arthritis (RA), Multiple Sclerosis (MS) and Low Back Pain (LBP) was studied. The sample was consisted of 67 LBP, 60 RA and 63 MS patients selected from Atieh, Imam Khomeini hospitals, and the Iranian MS Society in city of Tehran plus 65 nonpatient mothers. All participants answered Depression- Anxiety-Stress Scale (DASS-42; Laviband & Laviband, 1995) and the Parent-Child Relationship-Short form (PCRS-S; Pianta, 1992). Patient mothers also answered Visual Analogue Scale (VAS; Wewers & Lowe, 1990) and Pain related Disability Questionnaire (PDQ; Roland & Morris, 1983). Data were analyzed using variance analysis, Pearson correlation and stepwise regression. Results indicated that the depression severity differed significantly in patient and nonpatient mothers. Also, disability due to pain and conflict in mother-child relationship significantly predicted depression in mothers. Therefore, it was concluded that disability and conflict in mother-child relationship is related to depression severity in mothers with chronic illnesses.