The aim of this study was to assess periodontal knowledge and periodontal status in 20-60-year-old adult population in northern Jordan. A convenient sample consisting of 722 adults was included in this study. A questionnaire incorporating items related to socio-demographic and periodontal knowledge questions was completed before clinical examination, using the Community Periodontal Index of Treatment Needs (CPITN). The results showed that the proportions of subjects who reported bleeding gums, gums' irritation, rough tooth surface and gum disease decreased steadily with age, there is an evident linear trend with high statistical significant difference among various age groups (P < 0.001). Furthermore, the proportions of subjects who answered correctly the periodontal knowledge questions related to plaque definition and its role in disease aetiology and prevention, decreased with age, with a high significant difference for all knowledge questions (P < 0.001). The prevalence of subjects with healthy periodontium (score 0) decreased with age, being 41.1% among 20-29-year-old group and 11.1% in 50-60-year-old group. Similar trend was seen for bleeding on probing (score 1) whilst calculus deposit (score 2) was the major problem in all age groups over 29 years. The prevalence of periodontal pockets was relatively low, with a range of 4.5-18.6% for shallow pockets (score 3) and 2.9-11.1% for deep pockets in younger and older age groups, respectively. Younger age group had more healthy sextants than older age groups. In addition, sextants with bleeding on probing were highest in 20-29-year-old age group (1.8) compared with that in 50-60-year-old age group (0.60) whilst those with calculus deposits varied slightly among different age groups (1.50-1.65). Sextants affected by shallow or deep pockets increased steadily with age. Such a finding was also noted in excluded sextants, with an increase from 0.15 at 20-29 year-old group to 0.94 at the age of 50-60 years. It is concluded that health knowledge and status related to periodontal disease is still poor in northern Jordan. Therefore, dental health education provision is necessary to improve oral health knowledge and conditions among population in general and among older population in particular.