Line breaks in R Markdown text (not code blocks)

You can also use native LaTeX instructions if you use Knit to generate the PDF output. This would break the other output formats such as HTML though... :

e.g. :

In Markdown part

---
output: pdf_document
---

# test 1
No spaces used   

line1\linebreak
line2

line3\linebreak line4

\linebreak and \newline seem to both work...

As R expression
r paste0("test","\\linebreak ", "test2")

Output is :
test
test2

Don't forget to add a trailing space after "\linebreak "...

This also allows to center paragraphs.

See also : Centering image and text in R Markdown for a PDF report

It's a rather old question, but I post an answer since it's the first hit when googling for "line breaks in rmarkdown".

If compiling to pdf, you can use latex macros. Substitute the ** in the new line with \hfill\break:

# Introduction

The Tufte-\LaTeX\ [^tufte_latex] document**
\hfill\break
classes define a style similar to the style Edward Tufte uses in his books...

The best way I have found to add blank lines is:

# First title
<br><br><br><br><br>  

# Second title with 5 blank spaces above it

You can try this, hopefully it helps. I have tested in html_documents only, but presumably it would work in pdf as well.

I tried these tests, it seems to be working:

test.Rmd

---
output: pdf_document
---

# test 1
No spaces used   

line1
line2


# test 2
2spaces at the end of line1  

line1  
line2

# test 3
2spaces at the end of line1, then 2 spaces on next line

line1  

line2

sessionInfo()
R version 3.2.0 (2015-04-16)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 7 x64 (build 7601) Service Pack 1

locale:
[1] LC_COLLATE=English_United Kingdom.1252  LC_CTYPE=English_United Kingdom.1252   
[3] LC_MONETARY=English_United Kingdom.1252 LC_NUMERIC=C                           
[5] LC_TIME=English_United Kingdom.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

loaded via a namespace (and not attached):
[1] htmltools_0.2.6 tools_3.2.0     yaml_2.1.13     rmarkdown_0.5.1 digest_0.6.8